Oscillating fin propulsion has been used to produce efficient propulsion. This technology appears in U.S. Pat. No. 6,022,249 and U.S. Pat. No. 7,637,791 the text and drawings of which are expressly incorporated herein by reference, which discloses a novel water craft, such as a kayak or a stand up craft, which typically include a hull having propulsion means extending below the water line. The propulsion means comprises a pair of fins each having a leading edge and a trailing edge and adapted to oscillate through an arcuate path in a generally transverse direction with respect to the central longitudinal dimension of the watercraft. Foot operated pedals are operatively associated with the propulsion means for applying input force to the propulsion means. The propulsion means includes a pair of fins which twist to form an angle of attack for providing forward thrust with respect to the longitudinal dimension of the watercraft while moving in both directions along the arcuate path.
The existing fin designs are limited to relatively soft and flexible material to allow the flex and twist to assume the shape of a propeller blade.
The existing fin designs are solid and the weight is directly related to the volume.
The existing fin designs have generally a square tip end and is tapered span wise. The cord at the root of the current fin designs is larger than the cord at the tip end.